FIELD OF THE INVENTION
The present invention relates to a cured polyphenylene ether resin and a curable polyphenylene ether resin. More particularly, the present invention is concerned with a novel cured polyphenylene ether resin comprising a chloroform nonextractable polyphenylene ether and a chloroform extractable polyphenylene ether, and which is decomposable by pyrolysis gas chromatography to form various types of methyl-substituted phenols, particularly 3,5-dimethylphenol in a specific amount, and contains a relatively small amount of a chloroform extractable polyphenylene ether containing polyphenylene ether units substituted by an alkenyl group and/or an alkynyl group. The cured polyphenylene ether resin is excellent not only in mechanical properties and desired electrical properties, such as a low dielectric constant and a low dielectric dissipation factor, but also in heat resistance and chemical resistance. Therefore, the cured polyphenylene ether resin can advantageously be used as a dielectric material, an insulating material, a heat resistant material and the like in, for example, electrical and electronic industries.
The present invention is also concerned with a novel curable polyphenylene ether resin having a specific average substitution degree of an alkenyl group and/or an alkynyl group, which has not only excellent mechanical properties and desired electrical properties, such as a low dielectric constant and a low dielectric dissipation factor, but also excellent melt processability and storage properties.